Metabolic syndrome and prostate cancer risk in a population-based case-control study in Montreal, Canada

Abstract

Background: The role of metabolic syndrome (MetS) in prostate cancer risk is still debated. We investigated it in a large population-based case-control study.

Methods: Cases were 1937 men with incident prostate cancer, aged ≤ 75 years, diagnosed across French hospitals in the Montreal area between 2005 and 2009. Concurrently, 1995 population controls from the same residential area and age distribution were randomly selected from electoral list of French-speaking men. Detailed lifestyle and medical histories, and anthropometric measures, were collected during in-person interviews. Prevalence of MetS components (type 2 diabetes, high blood pressure, dyslipidemia and abdominal obesity) was estimated at 2 years before diagnosis for cases/ interview for controls, and at ages 20, 40, 50 and 60. Logistic regression was used to estimate odds ratios (OR) and 95 % confidence intervals for the association between MetS and prostate cancer risk.

Results: A history of MetS (≥ 3 components vs < 3) was associated with a reduced risk of prostate cancer (OR = 0.70 [0.60, 0.82]) after considering potential confounders. The negative association was particularly pronounced with a young age (≤ 40 years) at MetS onset (OR = 0.38 [0.16-0.89]), did not vary according to prostate cancer aggressiveness, and was only partly explained by the presence of type 2 diabetes. A risk decrease was observed with the number of MetS components, suggesting a synergistic interaction of the components.

Discussion: The observed negative association, consistent with results from other North American populations undergoing regular prostate cancer screening, underlines the importance of considering PSA-testing when studying the MetS-prostate cancer association.

Conclusions: Findings from this study are consistent with an inverse association between MetS and prostate cancer risk.

Fig. 1

Odds ratio^a for the risk of prostate cancer according to age at metabolic syndrome^b onset. ^aAdjusted for age, family history of prostate cancer, ancestry, prostate cancer screening and family income. ^bAccording to the definition of the Adult Treatment Panel III from the National Cholesterol Education Program with body mass index instead of waist circumference which was only measured at interview

Fig. 2

Odds ratio^a for the risk of prostate cancer according to number of metabolic syndrome components. ^aAdjusted for age, family history of prostate cancer, ancestry, prostate cancer screening and family income. The referent category was represented by subjects without any metabolic disorder